honestly, as long as it doesn't cause an allergic reaction, I see no harm. It's not like you have to sedate them, or stick them with real needles.
I think the six months was for cats with fur: it lasts until the fur falls out. On a sphinx, with little fur, its effects should be more like on human skin I would think.
Dr. Seuss~DLH (brother's cat)~June 2007-
Misty~DSH (my cat & Mooby's mom)-?-
MooBoots(Mooby) ~ DMH(Mom's cat)~July 21, 2008-
Sunshine~ Golden retriever X white german sheperd (Dad's dog)~October 24, 2008-